In dentistry making of a denture has to first forming a master mold according to the teeth profile of a patient, then forming the denture through the master mold. The material of the master mold generally is formed by mixing molding powder or gypsum with water. Mixing is done by hands to make the material evenly blended and viscous. The mixed material will be cured after a period of time. As mixing by hands takes a lot of labor and cannot last a very long time, and the material cannot be blended evenly, the material often has air bubbles inside and results in a porous and coarse surface on the finished mold. This affects the quality of the denture.
To remedy the aforesaid problem, mixers for dental molding material have been developed in prior art (one of such references is R.O.C. patent publication No. 274741). It includes a transmission apparatus with a planetary gear mechanism. The molding material is mixed by rotation and also by revolution about a sun gear so that it can be evenly blended at high speed rotation and receive centrifugal force to eliminate the air bubbles.
The mixer previously discussed has extensible springs to link the top of a motor with a seat. During operation the bottom of the motor is not being anchored and tends to sway excessively. As a result the motor and equipment mounted thereon are not being held steadily. To overcome this problem, Applicant has proposed a shock absorbing structure for mixers of dental molding material (R.O.C. patent No. M278472). It includes a plurality of bracing struts, a plurality of first extensible springs, a plurality of second extensible springs, a bottom board and a detention board. The first extensible springs bridge the top end of the corresponding adjacent bracing struts and the top of a motor. The second extensible springs bridge the bottom end of the adjacent bracing struts and the bottom of the motor. The bottom board is anchored on the bottom end of the bracing struts. The detention board has a central opening. The bracing struts run through the detention board and anchored on the middle portion of the bracing struts. The motor is confined in the central opening through the constraint of the extensible springs and suspended above the bottom board. Through the first and second extensible springs that are fastened to the top and bottom of the motor, the vibration generated by the motor during operation can be absorbed to enhance the steadiness of the motor and the equipment mounted thereon.
During transportation, to prevent the mixer from being swayed and impacted in the shock absorbing structure, a plurality of screws are used to tightly fasten the bottom of the mixer to the bottom board of the shock absorbing structure. But there is still a gap between the central opening and the mixer, friction or impact between the mixer body and the detention board frequently occurs during transportation. This could result in denting, fracturing or damaging of the mixer and the detention board. There is still room for improvement.